This invention relates generally to high frequency components and more particularly to packaging for high frequency components.
Monolithic microwave integrated circuits (MMIC) are becoming prevalent in microwave frequency communications systems. MMIC components are fabricated using techniques similar to those used to fabricate semiconductor circuits. The resulting circuits are thus very small. For example, an amplifier and a phase shifter fabricated using MMIC technology might both fit into a package with dimensions approximately 0.5".times.0.5".times.2".
MMIC components must be adequately packaged. The package, at a basic level, provides physical support for the component. Beyond that, the package also provides an hermetically sealed environment. Since the MMIC components have both RF and DC inputs, the package must accommodate two types of connections to the MMIC components.
Some MMIC packages are made with metal walls. A metal top and bottom are then brazed to the walls. Coaxial connectors run through the walls for RF connections and pins are placed through the walls for DC connections. Inside the package, flexicables are used to make connections to the MMIC components.
In another type of package, the walls are made from several layers of ceramic which is cofired to make a laminated ceramic wall. In some instances, conductive traces are deposited onto the separate ceramic layers before cofiring to pass RF and DC signals through the walls. Inside the package, flexicables complete the RF and DC connections to the MMIC components. The signal paths through the walls can be made by silk screening tungsten paste onto the ceramic.
While these laminated packages are adequate for many applications, it would be desirable to improve their construction. It might be desirable to simplify assembly of the package by eliminating the flexicable. Also, it might be desirable to reduce the lossiness of the RF feedthrough.